Annalee Newitz

As we move from paper books to e-books, the practice of reading before bed may have to change. A new study suggests that looking at the bright light of a tablet screen may be interfering with the natural production of hormones that aid in falling asleep.

Over at Scientific American, Stephani Sutherland writes:

Mariana Figueiro of the Lighting Research Center at Rensselaer Polytechnic Institute and her team showed that two hours of iPad use at maximum brightness was enough to suppress people's normal nighttime release of melatonin, a key hormone in the body's clock, or circadian system. Melatonin tells your body that it is night, helping to make you sleepy. If you delay that signal, Figueiro says, you could delay sleep. Other research indicates that "if you do that chronically, for many years, it can lead to disruption of the circadian system," sometimes with serious health consequences, she explains.